Oncostatin M: From Intracellular Signaling to Therapeutic Targets in Liver Cancer

Abstract

Primary liver cancers represent the third-most-common cause of cancer-related mortality worldwide, with an incidence of 80-90% for hepatocellular carcinoma (HCC) and 10-15% for cholangiocarcinoma (CCA), and an increasing morbidity and mortality rate. Although HCC and CCA originate from independent cell populations (hepatocytes and biliary epithelial cells, respectively), they develop in chronically inflamed livers. Evidence obtained in the last decade has revealed a role for cytokines of the IL-6 family in the development of primary liver cancers. These cytokines operate through the receptor subunit gp130 and the downstream Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathways. Oncostatin M (OSM), a member of the IL-6 family, plays a significant role in inflammation, autoimmunity, and cancer, including liver tumors. Although, in recent years, therapeutic approaches for the treatment of HCC and CCA have been implemented, limited treatment options with marginal clinical benefits are available. We discuss how OSM-related pathways can be selectively inhibited and therapeutically exploited for the treatment of liver malignancies.

Keywords: cholangiocarcinoma; epithelial–mesenchymal transition; hepatocellular carcinoma; inflammation; signaling; tumor microenvironment; tumor proliferation.

Figure 1

Different receptor binding for human and mouse OSM. OSM binds two different heterodimeric receptors: the type I receptor, formed by gp130 and LIFRβ, and the type II receptor, formed by gp130 and the OSM receptor β (OSMRβ). Human OSM can bind to both gp130/OSMRβ and gp130/LIFRβ, whereas murine OSM interacts only with the type II receptor. OSM: oncostatin M; LIFRβ: LIF receptor β.

Figure 2

Overview of the OSM signaling pathways. OSM–receptor hetero-dimerization drives JAKs’ recruitment. The C-terminal region of receptor types I and II contains tyrosine residues, which, phosphorylated by JAK1/2, act as a docking site for STAT1 and STAT3. OSM can also activate other downstream proteins such as ERK1/2, p38, JNK, the PI3K/Akt pathway, and PKCδ. OSM: oncostatin M; JAKs: Janus kinases; Erk1/2: extracellular-regulated kinase ½; PI3K: phosphatidylinositol 3-kinase; STAT: signal transducer and activator of transcription; JNK: Jun N-terminal kinase; PKC: protein kinase C.